Method and system for controlling rotational speed of an agitator or catheter

ABSTRACT

A method and device handle having a slide assembly for controlling rotational speed of a catheter assembly under various rotational loads. The method includes setting a first current limit in a processor, activating the catheter assembly to rotate, calculating a current value in rotational period of a first current limit, updating a second current limit from the first current limit, and wherein the second current limit is lower than the first current limit.

TECHNICAL FIELD

The present disclosure generally relates to a method and system forcontrolling rotational speed of an agitator or catheter and morespecifically to a method and system for controlling rotational speed foran agitator or catheter in a device handle of a medical device forcutting a substance from an inner wall surface of a body lumen.

BACKGROUND DISCUSSION

A thrombus, or blood clot, occurs in the vascular system as a result ofblood coagulation from injury or turbulent blood flow. Due to itsability to restrict blood flow, if a thrombus is generated in a vascularlumen, it should be removed. Deep vein thrombosis involves formation ofa thrombus in a vein existing in a deep part of the body such as afemoral vein or a popliteal vein. One danger of the presence of deepvein thrombosis (DVT) is that thrombi can dislodge and embolizeresulting in compromised pulmonary function.

Several methods have been developed to treat deep vein thrombosis. Onemethod is known in which a shaft main body of a catheter system isinserted into a blood vessel, and then an agent such as a thrombolyticagent is injected into an embolus portion to dissolve and remove thethrombus. However, this technology to remove thrombi is known to causebleeding. In addition, in coronary arteries a percutaneous transluminalcoronary angioplasty (PTCA) may be performed to open arteries affectedby plaque or thrombus formation. In this method, the blood vessel isdilated using a balloon, and a mesh-shaped or coil-shaped stent is leftto indwell the blood vessel as a support for the blood vessel. However,these methods are less likely to be applied when the plaque of thestenosed site becomes calcified or if the stenosed site develops in abifurcated portion of the coronary arteries.

A treatment has been proposed in which a thrombus is mechanically brokenand is suctioned out of the vascular lumen. The thrombus is subsequentlyremoved by a shaft main body inserted in a blood vessel. With thistreatment, it is possible to reduce or potentially eliminate the use ofthe agent entirely. Such a system is disclosed in U.S. Pat. No.6,024,751.

SUMMARY

A method and system is disclosed to ensure proper removal of a stenosedsite within a blood vessel and reduce the hazard on biological tissuesand/or blood vessels by stopping the rotation of an agitator or catheterassembly upon engagement with the biological tissues and/or bloodvessels.

A method is disclosed for controlling rotational speed of a catheterassembly under various rotational loads, the method comprising: settinga first current limit in a processor; activating the catheter assemblyto rotate; calculating a current value in a rotational period of a firstcurrent limit; updating a second current limit from the first currentlimit; and wherein the second current limit is lower than the firstcurrent limit.

A method is disclosed of limiting torque of a catheter assembly with arotational profile, the method comprising: setting a starting value fora current limit of a motor, the motor being configured to drive thecatheter assembly; calculating a motor current of the motor during adriving of the catheter assembly in a first direction; and updating thecurrent limit of the motor as a function of the current limit based onthe calculated motor current.

A device handle is disclosed for cutting substances inside a body lumen,the device handle comprising: a slide assembly, the slide assemblyincluding a drive shaft assembly configured to rotate a catheterassembly, a motor configured to impart a rotational force to the driveshaft assembly and the catheter assembly, and a processor, wherein theprocessor is configured to: drive the catheter assembly so that thecatheter assembly attains at a target rotational speed in a firstdirection; update a second current limit in the first direction from afirst current limit in the first direction, and wherein the secondcurrent limit in the first direction is lower than the first currentlimit in the first direction; if a rotational speed in the firstdirection was not achieved at the target rotational speed, setting afirst current limit in the second direction that is higher than thefirst current limit in the first direction when driving the catheterassembly so that the catheter assembly attains at the target rotationalspeed in a second direction; and alternate the driving of the catheterassembly between the first direction and the second direction.

A method is disclosed for controlling rotational speed of a catheterassembly under various rotational loads, the method comprising: drivingthe catheter assembly at a target rotational speed in a first directionpursuant to a rotational speed profile; driving the catheter assembly atthe target rotational speed in a second direction pursuant to therotational speed profile; and alternating the driving of the catheterassembly between the first direction and the second direction.

A method is disclosed of limiting torque of a catheter assembly with arotational profile, the method comprising: setting a starting value fora current limit a motor, the motor being configured to drive thecatheter assembly; measuring a motor current of the motor during adriving of the catheter assembly in a first direction; and updating thecurrent limit of the motor as a function of the current limit based onthe measured motor current.

A device handle is disclosed for cutting substances inside a body lumen,the device handle comprising: a slide assembly, the slide assemblyincluding a drive shaft assembly configured to rotate a catheterassembly, a motor configured to impart a rotational force to the driveshaft assembly and the catheter assembly, and a processor, wherein theprocessor is configured to: drive the catheter assembly at a targetrotational speed in a first direction pursuant to rotational speedprofile; drive the catheter assembly at the target rotational speed in asecond direction pursuant to the rotational speed profile; and alternatethe driving of the catheter assembly between the first direction and thesecond direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a handle with a slide assembly for usewith an agitator or catheter in accordance with an exemplary embodiment.

FIG. 1B is a cross-sectional view illustrating an agitator on a distalend of a catheter assembly in a blood vessel having a stenosed site inaccordance with an exemplary embodiment.

FIG. 2 is another perspective view of the handle with the slide assemblyfor use with the agitator or catheter in accordance with an exemplaryembodiment.

FIG. 3 is a perspective view of the handle and the slide assembly inaccordance with an exemplary embodiment.

FIG. 4 is a perspective view of a portion of the slide assembly inaccordance with an exemplary embodiment.

FIG. 5 is a perspective view of a catheter interface on the handle in aready position without an agitator.

FIG. 6 is a perspective view of the catheter interface on the handlewith the agitator shaft luer attached to the handle.

FIG. 7 is a perspective view of the catheter interface on the handlewith an agitator module inserted an outer sheath, and the agitator ispositioned on a distal end (or position) of a blood clot.

FIG. 8 is a perspective view of the catheter interface on the handle andwherein the outer sheath has pull back to deploy agitator.

FIG. 9 is a perspective view of the catheter interface on the handleafter the clamping plate has been installed over a luer.

FIG. 10 is rotational speed profile illustrating speed versusrevolutions in accordance with an exemplary embodiment.

FIG. 11 is a rotational speed profile illustrating current/torque versusrevolutions in accordance with an exemplary embodiment.

FIG. 12 is a rotational speed profile illustrating speed versusrevolutions in accordance with an exemplary embodiment.

FIG. 13 is a rotational speed profile illustrating current/torque versusrevolutions in accordance with an exemplary embodiment.

FIG. 14 is a rotational speed profile illustrating speed versusrevolutions in accordance with an exemplary embodiment.

FIG. 15 is a rotational speed profile illustrating current/torque versusrevolutions in accordance with an exemplary embodiment.

FIG. 16 is a cross-sectional view of a mechanical brake in accordancewith an exemplary embodiment.

FIG. 17 is a flow chart illustrating a first loop (i.e., loop 1 or firstcycle) illustrating speed control, current limit, and motion control foran exemplary system.

FIG. 18 is a flow chart illustrating a second loop (i.e., loop 2)illustrating speed control and motion control of an agitator of acatheter assembly of an exemplary system.

FIG. 19 is a flow chart illustrating a third loop (i.e., loop 3) fordetermining current limit of a motor controlling a catheter assembly ofan exemplary system.

FIG. 20 is a flow chart illustrating a routine for speed control,current limit, and motion control of an agitator of a catheter assemblyof an exemplary system.

FIG. 21 is a continuation of the flow chart illustrating the routine forspeed control, current limit, and motion control of the agitator of thecatheter assembly of the exemplary system of FIG. 20 in accordance withan exemplary embodiment.

FIG. 22 is a continuation of the flow chart illustrating the routine forspeed control, current limit, and motion control of the agitator of thecatheter assembly of the exemplary system of FIG. 20 in accordance withan exemplary embodiment.

FIG. 23 is a continuation of the flow chart illustrating the routine forspeed control, current limit, and motion control of the agitator of thecatheter assembly of the exemplary system of FIG. 20 in accordance withan exemplary embodiment.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure will be describedwith reference to the drawings. In order to facilitate description,dimensional ratios in the drawings are exaggerated and thus aredifferent from actual ratios in some cases.

FIG. 1A is a perspective view of a medical device 100, which includes ahandle 110 having a slide assembly 120 for use with a catheter assembly130 in accordance with an exemplary embodiment. As shown in FIG. 1A, themedical device 100 can be used for therapy (treatment) to cut a stenosedsite or an occluded site which is caused by plaque, thrombus or the likeinside the blood vessel (not shown). In this description, a side of thedevice 100, which is inserted into the blood vessel is referred to as a“distal side”, and an operating hand side is referred to as a “proximalside”.

As shown in FIG. 1A, the handle 110 includes a guide rail assembly 112having one or more tracks 114 configured to receive the slide assembly120. The catheter assembly 130 is configured to be attached or receivedon a distal portion 121 of the slide assembly 120. In accordance with anexemplary embodiment, the slide assembly 120 can include a plurality ofbearings, for example, ball bearing configured to run on a track 114 forsmoother operation. For example, in accordance with an exemplaryembodiment, the plurality of bearings can be four (4) 10 mm ballbearings.

In accordance with an exemplary embodiment, the medical device 100 ispreferably configured to have, for example, a manual pull back ofapproximately 250 mm to 350 mm, and preferably at least 300 mm. Forexample, on an inner surface 116 of the handle 110, a plurality ofmarkings or indicia 118 can be placed to help an operator determine anamount of axial displacement of the agitator of the catheter assembly130 during use. In accordance with an exemplary embodiment, the pullback is a manual control pull back only. As shown in FIG. 1A, the handle110 can include a plurality of cover plates, for example, a top frontcover plate and a back cover plate. In accordance with an exemplarydesign, for example, the handle 110 can have a height of approximately75 mm to 90 mm, a width of approximately 80 mm to 100 mm, and a lengthof approximately 300 mm to 400 mm.

In accordance with an exemplary embodiment, the handle 110 is preferablydesigned to detect and stop, for example, an agitator 132, which is partof the catheter assembly 130, when the agitator 132 engages a bloodvessel wall. For example, in accordance with an exemplary embodiment, acontrol system, for example, a processor or controller within the slideassembly 120 of the handle 110 can be configured to have a vesseldetection condition, which can detect with 180 degrees of vesseltwisting, and wherein the 180 degrees of vessel twisting is equal to 180degrees plus 90 degrees at Luer connection to the catheter assembly (orcatheter) 130. In accordance with an exemplary embodiment, the handle110 is configured that after detection of, for example, vessel twisting,the luer connection 210 to the catheter assembly 130 stops within 360degrees.

As illustrated in FIG. 1B, the catheter assembly 130 of the medicaldevice 100 can include an agitator 132. In accordance with an exemplaryembodiment, the agitator 132 can be arranged or located on a distal endor distal portion of the catheter assembly 130. The agitator 132 can be,for example, a cutting unit, which is expandable and contractibleradially outward. For example, the agitator 132 can be a mechanicalagitator along the treatment length of the catheter assembly 130 formechanically agitating a clot at the treatment site and/or fordispersing lytic at the treatment site. The mechanical agitator maycomprise a radially expansible agitator 132 that is rotatable and/oraxially translatable with the catheter assembly 130. In accordance withan exemplary embodiment, the radially expansible agitator 132 thecatheter assembly 130 may be self-expanding, for example, a Nitinol(Ni—Ti) cage 134. In accordance with an exemplary embodiment, theradially expansible agitator has a mass 136 on a distal end providingrotational inertia. For example, as shown in in FIG. 1B, the mass 136can be produced from a collection of the distal ends of the materialconstituting the radially expansible agitator 132, for example, theNitinol. In accordance with an exemplary embodiment, the agitator 132can have a helical shape and be configured to dilate and contract whenaccelerated and decelerated, respectively, due to the rotational inertiaand the helical design.

In accordance with an exemplary embodiment, for example, as aconfiguration material of the agitator 132, a shape memory alloy, whichis provided with a shape memory effect or super-elasticity by means ofheat treatment, or stainless steel, can be preferably used. As the shapememory alloy, Ni—Ti-based alloys, Cu—Al—Ni-based alloys, Cu—Zn—Al-basedalloys, and combinations of the shape memory alloys, are preferablyused.

In accordance with an exemplary embodiment, for example, the agitator132 of the catheter assembly 130 may comprise a resilient element thatmay be radially constrained to have a low profile (small diameter) andmay be freed from radial constraint to have an enlarged profile (largediameter) with a non-linear geometry. Radial constraint may be providedby a sleeve or sheath that may be axially advanced and retractedrelative to the catheter assembly 130 to cover and uncover the radiallyexpansible agitator. In this way, the catheter assembly 130 may beintroduced to a treatment site within the vasculature with theexpansible agitator 132 covered (and thus radially constrained). Afterthe desired treatment site S is reached, an outer sheath 230 (FIG. 7 )may be axially retracted to release the radially expansible agitator 132so that it expands to engage the clot in the blood vessel. The agitator132 may then be rotated and/or axially translated to engage and disruptthe clot in combination with the release, for example, of a thrombolyticagent.

FIG. 2 is another perspective view of the handle 110 with the slideassembly 120 for use with the agitator or catheter in accordance with anexemplary embodiment. As shown in FIG. 2 , the slide assembly 120 caninclude a drive module frame 122 configured to receive a drive shaftassembly 124. The drive shaft assembly 124 can include, for example, adrive shaft with a press fit gear and code wheel attachments 126. Inaccordance with an exemplary embodiment, for example, an extended motorshaft can be used to eliminate the need for a separate driving shaft.The slide assembly 120 also includes a motor 128. The drive shaftassembly 124 can include a drive gear, which meshes with the driven gear(or rotary shaft) of the motor 128. The motor 128 can serve as a drivesource including the rotary shaft to which the drive gear is fixed.

In accordance with an exemplary embodiment, the motor 128 can beconfigured to have an operating voltage, for example, of approximately 6to 12 V (volts). For example, in accordance with an exemplaryembodiment, the motor can be rated for 4.5 V to 15 V, having a hightorque constant, for example, around 6.5 mNm/A to 7.0 mNm/A, a speedconstant of approximately, 1350 RPM/V to 1400 RPM/V, and a max power of40 W at 12 V.

In accordance with an exemplary embodiment, the slide assembly 120 alsoincludes a plurality of electronic components 129, which can be mounted,for example, on a printed circuit board (PCB)(not shown). The electroniccomponents 129 are configured to carry out the processes as disclosedherein. The electronic components 129 can include, for example, aprocessor or a microprocessor, an operating system, one or more memoriesor memory cards, and/or a servo motor controller. In accordance with anexemplary embodiment, the processor has at least one from an instructionunit that instruct the motor controller and a calculating unit thatcalculates the current for example, the average current that monitoredabout 50 times per 1 mm second. The motor controller has at least onefrom a current supply unit to the motor, a decision unit that decideamount of the current to flow, a monitoring unit to monitor a flowingcurrent or a current to be flowed. The processor may decide amount ofthe current to flow. In accordance with an exemplary embodiment, thehandle 110 of the medical device 100 can include, for example, a powerjack, a USB port, a power switch and status LED, and an activate switch204 for the agitator 132.

For example, in accordance with an exemplary embodiment, the mechanicaldrive of the drive shaft assembly 124 can include an encoder and codewheel, which is configured to convert a reading from the code wheel intoa speed reading. For example, the encoder can be a three (3) channeloptical encoder, which uses, for example, a 500 counter per revolution(CPR) quadrature signal for motor control. In accordance with anexemplary embodiment, an index signal is sent to the processor to tracktotal revolutions. In accordance with an exemplary embodiment, ratherthan an encoder and code wheel, a speed sensor could be used.

In accordance with an exemplary embodiment, the drive shaft assembly 124can be configured to have an agitator 132 having a rotation speed ofbetween approximately 1100 RPM (revolutions per minute) to 12000 RPM,and having a rotational direction in each of a first direction and asecond direction (i.e., clockwise and counterclockwise) s at the targetagitator speed from four (4) revolutions to sixteen (16) revolutionsdepending on vessel patency. For example, when a clot (i.e., blood clot)completely closes the blood vessel and blood flow stops, the vesselpatency (i.e., openness of blood vessel) is 0%. When the blood flows ina healthy situation, the blood vessel patency is 100%. In accordancewith an exemplary embodiment, vessel patency of 50% to 100% can beacceptable as a successful execution of a treatment in a medicalguideline or procedure. For example, in accordance with an exemplaryembodiment, the rotating speed of the agitator 132 can obtain thefollowing patency: 1100 RPM, 40% patency; 1600 RPM, 50% patency; 3200RPM, 100% patency; 10000 RPM, 100% patency; 12000 RPM, 100% patency(trauma).

In accordance with an exemplary embodiment, for example, the drive shaftassembly 124 is preferably configured, for example, to have a peakagitator speed or target of approximately 3200 RPM (revolutions perminute), a maximum speed of approximately 4000 RPM, and a speed ofapproximately 3 revolutions of the agitator of the catheter assembly 130at approximately 2000 RPM, for 8 revolutions.

In accordance with an exemplary embodiment, the slide assembly 120 canbe programmed to rotate the agitator of the catheter assembly in amanner, which includes eight (8) clockwise revolutions, a rest periodof, for example, 500 milliseconds (msec), and eight (8)counter-clockwise revolutions. In accordance with an exemplaryembodiment, the process repeats after a 500 msec rest period. Inaccordance with an exemplary embodiment, the slide assembly 120 can beprogrammed or configured such that the rotation of the agitator of thecatheter assembly includes eight (8) clockwise revolutions (firstdirection), a coast period (or coast time) in which the agitator or thecatheter assembly is not under a rotational load (for example, 3 to 6revolutions, and more preferably 4 to 5 revolutions), a rest period of,for example, 500 milliseconds (msec), and 8 (eight) counter-clockwiserevolutions (second direction). In accordance with an exemplaryembodiment, the process repeats after another coast period (coast time),for example, 3 to 6 revolutions, more preferably 4 to 5 revolutions, anda 500 msec rest period. In accordance with an exemplary embodiment, forexample, the coast period and the rest period can be 0.4 seconds to 0.6seconds, and more preferably, are about 0.5 seconds.

FIG. 3 is a perspective view of the slide assembly 120 of the handle 110and a drive module assembly 124 in accordance with an exemplaryembodiment. As shown in FIG. 3 , the handle 120 can also include a powersupply 125, for example, one or more batteries 127. In accordance withan exemplary embodiment, the one or more batteries 125 preferably have abattery life of at least 2.0 hours or more of motor operation. Inaddition, or alternatively, the slide assembly 120 can include an AC/DCsource.

FIG. 4 is a perspective view of a portion of the slide assembly 120 inaccordance with an exemplary embodiment. As shown in FIG. 4 , the slideassembly 120 can include the drive module frame 122 configured toreceive the drive shaft assembly 124. The drive shaft assembly 124 caninclude, for example, a stainless steel shaft with a press fit gear andcode wheel attachments 126. In addition, in accordance with an exemplaryembodiment, one or more batteries 125 can be provided as a power source127.

FIGS. 5 and 6 are perspective views of a catheter interface 200 on thehandle 110 in a ready position without an agitator, and with an agitatorshaft luer 210 attached to a distal end of the drive shaft assembly 124,respectively. As shown in FIGS. 5 and 6 , the catheter interface 200 caninclude a connector 210, for example, a male fitting on a distal end ofthe drive shaft assembly 124 and which is configured to receive aconnector 220, for example, a female connection or shaft luer (or luerlock interface) on a proximal end of the catheter assembly 130.

In accordance with an exemplary embodiment, as shown in FIGS. 5 and 6 ,the slide assembly 120 of the handle 110 can include a grip feature 202having a width, for example, of about 65 mm to 75 mm, for example, 70mm, and arranged to have a right handed thumb located at position 1 201,the middle finger of the right hand at position 2 203, and the indexfinger of the right hand at position 3 205, which can push theactivation switch 204, which activates the rotation of the agitator 132.As shown, the handle 120 is designed to be operated by a user's righthand. In accordance with an alternative embodiment, the position of theactivation switch 204, for example, can be moved to an opposite side,such that the slide assembly 120 of the handle 110 can be operated by auser's left hand.

FIG. 7 is a perspective view of the catheter interface 200 on the handlewith the catheter assembly 130 and the agitator (or agitator module)(not shown) inserted an outer sheath 230 the agitator is positioned on adistal end (or distal position) of a blood clot. As shown in FIG. 7 ,the agitator of the catheter assembly 130 is inserted into the outersheath 230 and positioned on the distal end or side of the blood clot. Aconfiguration material of the catheter assembly 130 and the outer sheath230 is not particularly limited. However, for example, polyolefin suchas polyethylene, polypropylene and the like, polyamide, polyester suchas polyethylene terephthalate or the like, fluorine-based polymer suchas ETFE and the like, polyether ether ketone (PEEK), or polyimide, canbe preferably used for the catheter assembly 130 and the outer sheath230. In addition, the catheter assembly 130 and the outer sheath 230 maybe configured to include multiple materials, or a reinforcing materialsuch as a wire may be incorporated therein.

In accordance with an exemplary embodiment, as shown in FIG. 7 , thecatheter interface 200 also includes a receiving area 240 configured toreceive a luer (or tee connection 232 on a proximal end 234 of the outersheath 230. As shown in FIG. 7 , the receiving area 240 can have a pairof side walls 242, 244, and rounded or oval shaped receiving portion246.

FIG. 8 is a perspective view of the catheter interface 200 on the handleand wherein the tee connection 232 of the outer sheath 230 is pullbacked to deploy the agitator (not shown of the catheter assembly 130.As shown in FIG. 8 , the agitator of the catheter assembly 130 can bedeployed on the distal end or side of the blood clot at which time, theluer (or tee assembly) 232 on the proximal end 234 of the outer sheath230 can be moved proximally and placed within the receiving area 240.

FIG. 9 is a perspective view of the catheter interface 200 on the slideassembly 120 of the handle 110 after a clamping plate 242 has beeninstalled over the luer (or tee) 232. As shown in FIG. 9 , the clampingplate 242 can include a recess 244, which helps secure the luer (or tee)232 within the receiving area 240. In accordance with an exemplaryembodiment, the luer (or tee) 232 can be a tissue plasminogen activator(TPA) luer or tee 232.

FIG. 10 is rotational speed profile 300 illustrating speed versusrevolutions in accordance with an exemplary embodiment. As shown in FIG.10 , in accordance with an exemplary embodiment, during use of thehandle 110 and the sliding assembly 120 to remove a blood clot, thespeed 310 of the agitator of the catheter assembly 130 graduallyincreases to a target agitator speed of, for example, approximately 3200RPM, and then decreases. As shown in FIG. 10 , for a predetermine numberof revolutions, for example, 8 revolutions, in the first or seconddirection as disclosed herein at a target rotational speed, a portion ofthe 8 revolutions, i.e. at initial startup will be performed at less thetarget rotational speed of 3200 RPM.

FIG. 11 is a rotational speed profile 400 illustrating current/torqueversus revolutions in accordance with an exemplary embodiment. As shownin FIG. 11 , and in accordance with an exemplary embodiment, the drivemotor 128 can be controlled by the electronic components 129, forexample, a processor, a microprocessor, or controller, such that thedrive motor 128 follows the speed profile as shown in FIG. 10 , however,the circuitry 129 does not allow the current to exceed a predeterminedor predefined limit 410 as shown in FIG. 11 . As shown in FIG. 11 ,after an initial peak, the current is only allowed to drop below thecurrent limit 410, or stays the same. Thus, by limiting the torque, anoperator of the medical device 100 can detect and stop the agitator 132when the medical device 100 engages the blood vessel wall.

For example, in accordance with an exemplary embodiment, the devicehandle 100 can be configured to control a rotational speed of a catheterassembly 130, for example, an agitator 132 under various rotationalloads. As set forth above, the device handle 110 can include the slideassembly 120 having a drive shaft assembly 124 configured to rotate thecatheter assembly 130, the motor 128 configured to impart a rotationalforce to the drive shaft assembly 124 and the catheter assembly 130, anda processor, which carries out the process of driving a catheterassembly 130 at a target rotational speed in a first direction (forexample, clockwise), and stopping the rotational direction when apredetermined torque limitation is exceeded.

In accordance with an exemplary embodiment, the processor can beconfigured to carry out a process of further changing the rotationaldirection of the catheter assembly 130 from the first direction to asecond direction (for example, counterclockwise), monitoring therotational speed of the catheter assembly 130, and updating thepredetermined torque limitation to achieve the target rotational speedfor the rotational direction of the catheter assembly 130 in a samedirection as the rotational speed of the catheter assembly 130 obtainedduring the monitoring of the rotational speed. In accordance with anexemplary embodiment, if the rotational speed is less than the targetrotational speed, the processor can increase an initial current (orstarting current) for a next cycle of the rotational direction of thecatheter assembly 130.

In accordance with an exemplary embodiment, the changing of therotational direction of the catheter assembly 130 can include reducingthe torque applied to the catheter assembly 130 to zero after apredetermined number of rotations in the first direction, allowing thecatheter assembly to come to a stop, and stopping the rotation of thecatheter assembly 130 for a predetermined time before rotating thecatheter assembly 130 in the second direction. In addition, the processcan include rotating the catheter assembly in the second direction forthe predetermined number of rotations in the second direction, reducingthe torque applied to the catheter assembly to zero after thepredetermined number of rotations in the second direction, allowing thecatheter assembly to come to a stop, and stopping the rotation of thecatheter assembly for the predetermined time before rotating thecatheter assembly in the first direction. The rotation of the catheterassembly 130 in the first and the second directions can be repeated asneeded to treat, for example, a stenosed site within a blood vessel. Forexample, in accordance with an exemplary embodiment, the device handle100 can be used for the insertion of the catheter assembly 130 into abody lumen, the catheter assembly 130 including an agitator 132,arranging the agitator 132 on a distal side of a stenosed site in thebody lumen, and cutting the stenosed site inside the body lumen with theagitator 132.

FIG. 12 is a rotational speed profile 500 illustrating speed versusrevolutions in accordance with an exemplary embodiment, and FIG. 13 is achart 600 illustrating current/torque versus revolutions correspondingto the speed as shown in FIG. 12 . As shown in FIGS. 12 and 13 , if theactual speed drops a predetermined percentage, for example, Y percentage(Y %) over X ms (X milliseconds), in accordance with an exemplaryembodiment, a brake or stopping mechanism can be applied to the motor128. For example, in accordance with an exemplary embodiment, instead ofusing the motor to stop or slow (i.e., brake) the agitator 132, amechanical brake pad 920 (FIG. 16 ) could be used. In addition, duringdetection of the actual rotational speed of the catheter assembly 130,the signal received may suffer from unwanted modifications that cancause the reading to be inaccurate (i.e., noise). In accordance with anexemplary embodiment, average speed values may be used to address theunwanted modifications or noise, which may be experienced during thecapture, storage, transmission, processing, or conversion of the signalcorresponding to the actual rotational speed of the catheter assembly130.

In accordance with an exemplary embodiment as shown, for example, inFIGS. 12 and 13 , the device handle 100 can control the torque of acatheter assembly 130 under various rotational loads by driving thecatheter assembly 130 at a target rotational speed in a first direction(for example, clockwise), detecting an actual rotational speed of thecatheter assembly 130 in the first direction, comparing the targetrotational speed and the actual rotational speed of the catheterassembly 130 in the first direction, and stopping the driving of thecatheter assembly 130 in the first direction before a completion ofpredetermined number of rotations in the first direction when the actualrotational speed decreases a predetermined percentage over apredetermined time frame. In addition, as disclosed above, the processcan be applied to a second direction, for example, counterclockwise.

FIG. 14 is a rotational speed profile 700 illustrating speed versusrevolutions in accordance with an exemplary embodiment, and FIG. 15 is arotational speed profile 800 illustrating current/torque versusrevolutions corresponding to the speed as shown in FIG. 15 . As shown inFIGS. 14 and 15 , if the actual speed matches the target speed for thecycle, no change is needed. However, if the actual speed is below targetspeed, the initial current limit can be increased for the next cycle.

FIG. 16 is a cross-sectional view of a mechanical brake 900 inaccordance with an exemplary embodiment. As shown in FIG. 16 , themechanical brake 900 can include a solenoid 910 and a brake pad 920.Upon receiving a signal from the processor, the solenoid 910 presses thebrake pad 920 outward against the motor shaft 930.

FIG. 17 is a flow chart illustrating a first loop (i.e., loop 1 or firstcycle) 1100 illustrating speed control, current limit, and motioncontrol for an exemplary system. As shown in FIG. 17 , in the first loop1100, the cycle includes a speed control, a current limit, and a motioncontrol. As shown, for example in FIG. 10 , during use of the handle 110and the sliding assembly 120 to remove a blood clot, the speed 310 ofthe agitator 132 of the catheter assembly 130 gradually increases to atarget agitator speed of, for example, approximately 3200 RPM. Once thetarget agitator speed is obtained, for example of 3200 RPM for a definednumber of cycles, the agitator speed is then reduced or decreased (i.e.,ramps down, for example, by cutting the current to the motor 120 (andagitator 132), and allowing the agitator 132 to coasting to zero (0)RPM. The rotational direction of the agitator 132 is then changed (i.e.,clockwise to counterclockwise or counterclockwise to clockwise). Asshown in FIG. 17 , for example, for a predetermine number ofrevolutions, for example, 8 revolutions, in the first direction (i.e.,clockwise or counterclockwise) or a second direction (i.e.,counterclockwise or clockwise) as disclosed herein at a targetrotational speed, a portion of the 8 revolutions, i.e. at initialstartup will be performed at less the target rotational speed of 3200RPM.

As shown in FIG. 17 , for example, as shown in the rotational speedprofile 400 illustrated in FIG. 11 , the drive motor 128 can becontrolled by the electronic components 129, for example, a processor, amicroprocessor, or controller, such that the drive motor 128 follows thespeed profile as shown in FIG. 10 , however, the circuitry 129 does notallow the current to exceed a predetermined or predefined limit 410 asshown in FIG. 11 . As shown in FIG. 17 , the current limit can bepreset, or alternatively calculated by loop 3 1200 (FIG. 19 ). Thecurrent is measured at the target rotational speed and the current limitcan be updated based on measured current at the target rotational speed.The current is then cut (i.e., no longer provided to the motor 128driving the catheter assembly 130 and the catheter assembly 130 (i.e.,agitator 132) will coast to a stop for a change in the rotationaldirection of the agitator. Thus, by limiting the torque, an operator ofthe medical device 100 can detect and stop the agitator 132 when themedical device 100 engages the blood vessel wall.

In addition, in the first loop 1000, for example, the processor can beconfigured to monitor (i.e., detect) the number of rotations of theagitator 132, and further carry out a process of changing the rotationaldirection of the catheter assembly 130 from the first direction to asecond direction (for example, counterclockwise). In addition, once thepredetermined number of rotations has been completed, for example, 8revolutions, the processor can be configured to pause (i.e., completelystop the rotation) the catheter assembly 130 (and agitator 132) for apredetermined period of time, for example, 0.5 seconds, and once thepredetermined period of time has elapsed, the direction of rotation ofthe agitator 132 can be changed completing the first loop 1000.

FIG. 18 is a flow chart illustrating a second loop (i.e., loop 2) 1100illustrating speed control and motion control of the agitator 132 of thecatheter assembly 130 of an exemplary system. As shown in FIG. 18 , therotational speed profile 500 as illustrated in FIG. 12 andcurrent/torque versus revolutions as illustrated in FIG. 13corresponding to the speed as shown in FIG. 12 can be used to controlthe speed and current supplied to the agitator 132. For example, at thestart of a subsequent loop (for example, a second loop (i.e., loop 2),the speed (i.e., detected speed) of the agitator 132 can be comparedwith a predetermined target to determine if the rotational speed of theagitator 132 is exceeding the predetermined target speed, or operatingat a reduced speed (i.e., under or less than the predetermined targetspeed). For example, if the rotational speed is within a range of thepredetermined target speed (i.e., RPM), the current being providing tothe motor 128 driving the catheter assembly 130 and the agitator 132 canbe approved and no changes are needed.

Alternatively, as shown in FIGS. 12, 13, and 18 , if the actual speed ofthe catheter assembly 130 and the agitator 132 drops a predeterminedpercentage, for example, Y percentage (Y %) over X ms (X milliseconds),an emergency situation may arise, such that a brake or stoppingmechanism can be applied to the motor 128, for example, an inversecurrent brake. For example, in accordance with an exemplary embodiment,instead of using the motor to stop or slow (i.e., brake) the agitator132, a mechanical brake pad 920 (FIG. 16 ) could be used. In addition,during detection of the actual rotational speed of the agitator 132 ofthe catheter assembly 130, the signal received may suffer from unwantedmodifications that can cause the reading to be inaccurate (i.e., noise).In accordance with an exemplary embodiment, average speed values may beused to address the unwanted modifications or noise, which may beexperienced during the capture, storage, transmission, processing, orconversion of the signal corresponding to the actual rotational speed ofthe catheter assembly 130. If the emergency brake is activated, forexample, the speed of the agitator is preferably confirmed to be zero(0) RPM and the operation is reset, i.e., for example, as shown in thefirst loop 1000.

FIG. 19 is a flow chart illustrating a third loop (i.e., loop 3) 1200for determining current limit of a motor 128 of a catheter assembly 130of an exemplary system. As shown in FIG. 19 , the cycle is started andif a constant state speed (i.e., RPM) is recorded or detected, theconstant state speed is compared to the predetermined target speed, forexample, 3200 RPM, and the initial current limit can be evaluated, forexample, over the detected 8 revolutions. If the actual speed, forexample, matches the target speed for the cycle, no change is needed tothe current provided to the motor 128 and the initial current limit canbe maintained or kept the same. However, if the actual speed is belowthe target speed (i.e., too low), or alternatively, greater than thetarget speed (i.e., too high) the initial current limit of the motor 128can be increased or decreased for the next cycle. In accordance with anexemplary embodiment, the change in the current limit can be for thenext cycle in a same rotational direction as the detect speed, oralternatively, the change in the current limit can be for the nextrotation in a different rotational direction.

FIG. 20 is a flow chart 1300 illustrating a process 1310 for speedcontrol, current limit, and motion control of an agitator of a catheterassembly of an exemplary system in accordance with an exemplaryembodiment. As shown in FIG. 20 , initially, in step 1320, the system ispowered “ON”. Once the system is powered “ON” in step 1320, in step1330, an initial set of values of operational parameters (i.e.,predetermined values and predetermined operating conditions), forexample, on the controller or microcontroller (i.e., the processor orthe microprocessor, and/or one or more memories or memory cards). Inaccordance with an exemplary embodiment, the initial values andoperating parameters can include a set constant set values, which caninclude target angle of rotation, speed of rotation criterial for Loop 21100 (i.e., speed control and motion control of the agitator 132 of thecatheter assembly 130), brake time, and speed profile. In addition,variables parameters, are initially set values, which are stored in thecontroller (or microcontroller) and updated each cycle, which caninclude current limit and direction of rotation, for example, of theagitator. In step 1340, a determination is made, if the activationswitch of the system is set to either “ON” or “OFF”. In step 1342, ifthe system activation switch is in the “OFF” position, the processcontinues to step 1344 which sets the motor control status to “disabled”and the process returns to step 1340 until the system activation switchis changed to “ON”.

If the system activation switch is changed to “ON”, in step 1346, theprocess continues to step 1350 wherein predetermined or set values andvariables for the motor controller for current limit and target speed ofrotation are input into the controller. In step 1360, after setting thevalues and variables for the motor controller, the motor controllerstatus is set or changed to “enabled”. In step 1362, the average currentvalue from the motor controller is collected. In step 1364, a newcurrent limit value is calculated based on the actual average currentvalue and the controller is updated with the calculated new currentlimit value as the current limit. The calculated new current limit islower than the previous current limit. A new current limit value may becalculated based on the current value that is not averaged, for example,raw current data that monitored by the motor controller beforecalculating the average. In step 1370, upon operation of the catheterassembly, a stable speed of the rotation of the system by (i.e.,processor and/or memory and speed sensor) of the system is collected. Instep 1380, an actual angle of rotation is evaluated (i.e., calculated)and if the actual angle of rotation is equal to or less than a set value(i.e., predetermined value), the process continues to step 1600 as shownin FIG. 23 .

Alternatively, if the actual angle of rotation as calculated in step1380 is greater than the set value (or predetermined value), the processcontinues to step 1382. In step 1382, the speed of rotation value is setto zero (0) and the value is sent to the motor controller. The processthen continues to step 1384, wherein the determination of the brake timeis started and the process continues to step 1400 as shown in FIG. 21 .

FIG. 21 is a flow chart 1900 illustrating for evaluating calculatedaverage speed of rotation for a cycle of an agitator of a catheterassembly in accordance with an exemplary embodiment, for example, asshown in Loop 3 (1200). As shown in FIG. 21 , the process starts at step1910 where the average speed of rotation for a cycle is calculated. Instep 1920, if the average speed is less than the set value, the currentlimit value is set higher than the initial value of this cycle for thenext same direction operation. In step 1930, if the average speed isequal to the set value, the current limit value is set to the same valueas the initial value for the next same direction operation. In step1940, if the average speed is greater than the set value, the currentlimit value is set lower than the initial value of this cycle for thenext same direction operation. After each of steps 1920, 1930, and 1940,the direction of rotation, for example, of the agitator, is reversed, orset in an opposite direction as shown, for example, in step 1410 of FIG.22 .

FIG. 22 is a continuation of the flow chart 1300 illustrating theroutine for speed control, current limit, and motion control of theagitator of the catheter assembly of the exemplary system of FIG. 20 .As shown in FIG. 22 , in step 1410, the controller sets the direction ofrotation in a direction opposite to current direction. In step 1420,current brake time is calculated. In step 1420, if the brake time isless than or equal to the set time than the brake time is recalculated.If the brake time is greater than the set value, the process continuesto step 1430, where the load value is set and the process continues tostep 1332 and returns to step 1340 for determination if the activationswitch of the system is “ON” or “OFF” of FIG. 20 .

FIG. 23 is a continuation of the flow chart 1600 illustrating theroutine for speed control, current limit, and motion control of theagitator of the catheter assembly of the exemplary system of FIG. 20 .As shown in FIG. 23 , in step 1610, a rotational speed value for thesystem (i.e., speed of rotation value) is collected in one predeterminedtime. In step 1620, a determination is made if the collected speed ofrotation decreases a predetermined percentage over a predetermined time.If the collected speed of rotation in step 1620 has not decreased apredetermined percentage over the predetermined time, the processcontinues to step 1334. However, if the collected speed of rotation instep 1620 has decreased a predetermined percentage over thepredetermined time, the process continues to step 1630 in which a safestate routine is performed. In step 1640, the speed of rotation value isset to zero (0), and the value is sent to the motor controller. In step1650, the motor controller is instructed to enter into a disabled state.In step 1660, the motor controller enters the disabled state and theroutine is stopped

The detailed description above describes a device handle for a medicaldevice and treatment method. The invention is not limited, however, tothe precise embodiments and variations described. Various changes,modifications and equivalents can be effected by one skilled in the artwithout departing from the spirit and scope of the invention as definedin the accompanying claims. It is expressly intended that all suchchanges, modifications and equivalents which fall within the scope ofthe claims are embraced by the claims.

What is claimed is:
 1. A method for controlling rotational speed of acatheter assembly under various rotational loads, the method comprising:rotating the catheter assembly according to an initial peak current anda first current limit set in a processor, the first current limit beingless than the initial peak current, and wherein initial peak current andthe first current limit are configured to control a rotational speed ofthe catheter assembly at a target rotational speed; limiting, by theprocessor, an actual current value during a rotational period of thecatheter assembly to the first current limit after the initial peakcurrent; calculating, by the processor, the actual current value duringthe rotational period of the catheter assembly with the first currentlimit; and changing, by the processor, the first current limit to asecond current limit when the calculated actual current value by theprocessor during the rotational period of the catheter assembly with thefirst current limit is lower than the first current limit.
 2. The methodof claim 1, comprising: monitoring, by the processor, the current valueduring a plurality of rotational periods of the first current limit; andwherein the second current limit based on the actual current valuecollected in the plurality of rotational periods of the first currentlimit is set in the processor.
 3. The method of claim 2, comprising:setting, by the processor, the second current value based on an averagecurrent value in the plurality of rotational periods of the firstcurrent limits.
 4. The method of claim 3, wherein a rotational period ofthe second current limit is a series of rotational periods of the firstcurrent limit.
 5. The method of claim 1, comprising: calculating, by theprocessor, a current value in a rotational period with the secondcurrent limit; and changing, by the processor, the second current limitto a third current limit calculated based on the calculated currentvalue in the rotational period from the second current limit when thethird current limit is lower than the first current limit and the secondcurrent limit.
 6. The method of claim 1, further comprising: alternatinga rotational direction of the catheter assembly between a firstdirection and a second direction.
 7. The method of claim 6, wherein therotational direction of each of the first direction and the seconddirection at the target rotational speed is eight revolutions.
 8. Themethod of claim 7, further comprising: a period of time in which thecatheter assembly is not under a rotational load after the rotationaldirection of the catheter assembly in the first direction and the seconddirection at the target rotational speed, the period of time in whichthe catheter assembly is not under the rotational load includes a coastperiod in which the catheter assembly rotates and a rest period in whichthe catheter assembly does not rotate.
 9. The method of claim 7, whereinthe target rotational speed is up to 3200 revolutions per minute, andthe period of time in which the catheter is not under the rotationalload is 0.4 seconds to 0.6 seconds.
 10. A method of limiting torque of acatheter assembly with a rotational profile, the method comprising:rotating the catheter assembly at a target rotational speed according toan initial peak current and a starting value for an initial currentlimit for a motor, the starting value for the initial current limitbeing less than the initial peak current; limiting, by the processor, amotor current during a rotational period of the catheter assembly to theinitial current limit after the initial peak current; calculating, by aprocessor, the motor current of the motor during a rotation of thecatheter assembly in a first direction; and changing, by the processor,the initial current limit of the motor as a function of the initialcurrent limit based on the calculated motor current by the processorwhen the calculated motor current of the motor during the rotation ofthe catheter in the first direction is less than the initial currentlimit of the motor.
 11. The method of claim 10, wherein the startingvalue for the initial current limit is set in the processor to a defaultvalue when the catheter assembly is first activated.
 12. The method ofclaim 10, wherein after the catheter assembly completes the rotationalprofile, the method further comprising: decreasing, by the processor,the changed initial current limit gradually when the calculated motorcurrent of the motor during the driving of the catheter in the firstdirection in less than the starting value for the current limit of themotor.
 13. The method of claim 10, further comprising: alternating arotational direction of the catheter assembly between a first directionand a second direction.
 14. The method of claim 13, wherein therotational direction of each of the first direction and the seconddirection at the target rotational speed is eight revolutions at thecurrent limit of the motor and the changed current limit of the motor.15. The method of claim 10, further comprising: a period of time inwhich the catheter assembly is not under a rotational load after therotational direction of the catheter assembly in the first direction andthe second direction at the target rotational speed, the period of timein which the catheter assembly is not under the rotational loadincluding a coast period in which the catheter assembly rotates and arest period in which the catheter assembly does not rotate.
 16. Themethod of claim 15, wherein the target rotational speed is up to 3200revolutions per minute, and the period of time in which the catheter isnot under the rotational load is 0.4 seconds to 0.6 seconds.
 17. Adevice handle for cutting substances inside a body lumen, the devicehandle comprising: a slide assembly, the slide assembly including adrive shaft assembly configured to rotate a catheter assembly, a motorconfigured to impart a rotational force to the drive shaft assembly andthe catheter assembly, and a processor, wherein the processor isconfigured to: rotate the catheter assembly according at an initial peakcurrent and a first current limit, the first current limit being lessthan the initial peak current, and wherein initial peak current and thefirst current limit are configured to attain a target rotational speedin a first direction; limit an actual current value during a rotationalperiod of the catheter assembly to the first current limit in the firstdirection after the initial peak current; calculate the actual currentvalue during the rotational period of the catheter assembly with thefirst current limit in the first direction; change the first currentlimit in the first direction to a second current limit in the firstdirection when the calculated actual current value by the processorduring the rotational period of the catheter assembly with the firstcurrent in the first direction is lower than the first current limit inthe first direction; when a rotational speed in the first direction isnot achieved at the target rotational speed, changing by the processor,a first current limit in the second direction that is higher than thefirst current limit in the first direction calculated by the processorwhen driving the catheter assembly so that the catheter assembly attainsthe target rotational speed in a second direction; and alternate thedriving of the catheter assembly between the first direction and thesecond direction.
 18. The device handle of claim 17, wherein when therotational speed in the first direction exceeds the target rotationalspeed, setting the first current limit in the second direction that islower than the first current limit in the first direction so that thecatheter assembly attains the target rotational speed in the seconddirection.
 19. The device handle of claim 17, wherein when therotational speed in the first direction is achieved, setting the firstcurrent limit in the second direction that is the same as the firstcurrent limit in the first direction so that the catheter assemblyattains the target rotational speed in the second direction.
 20. Thedevice handle of claim 17, wherein the rotational direction of each ofthe first direction and the second direction at the target rotationalspeed is eight revolutions.